And how does Tolkien stack up by her proposed standard? Well, we've had a Tolkien Society for decades -- indeed, several societies. But I think she overestimates the importance of that in establishing an author's reputation. After all, at a glance how are we to distinguish between a gathering of like-minded scholars and a fan club? Browning had one, Harry Potter has the other; Tolkien's societies have tended to be a bit of both.
As for her second standard, Tolkien scholarship is lagging far behind C. S. Lewis in this regard: CSL has been the subject of no less than three major biographies (Green-Hooper, Sayer, and Wilson), his diary is in print (as well as a generous selection of his brother's diaries, which are far superior), and we now have a massive three-volume (4000 pages) COLLECTED LETTERS, plus three or four collections of memoirs and recollections. By contrast with Tolkien we have to content ourselves with the authorized biography (excellently supplemented by Garth and Scull & Hammond) and the selected letters, both more than three decades old now.
That would seem to indicate that Tolkien has yet to arrive, so far as the Academy is concerned -- something also backed up by T. A. Shippey's observation about all the major literary journals who've never published a single piece on JRRT.
But there are some more metrics I think relevant that Marler fails to take into account. One I've been v. much aware of is the publication of scholarly editions of an author's rough drafts, showing how their works were put together. We've had this for years with Woolf, but the supreme example remains THE JAMES JOYCE ARCHIVE, which reproduces in facsimile every page of Joyce's literary manuscripts, page proofs, &c known to survive in sixty-three huge folio volumes. Here Tolkien triumphs: the treatment of his drafts and unpublished literary manuscripts is unparalleled in being both massively detailed and wildly popular (the JJA never got hardcover AND mass-market paperback editions, for example). Here's also where Tolkien's posthumous trajectory has been more in line with the treatment accorded 'canonical' authors than has CSL's -- partly no doubt because Tolkien left behind masses of manuscripts of vast interest to his readers, while relatively few of Lewis's manuscripts survive, and the treatment of Walter Hooper when he published one of the more significant ones, THE DARK TOWER, was not such as wd encourage any editor to release more material.
One more metric I'd argue is predictive of creeping canonization is the outpouring of dissertations focused on Tolkien's work -- something that marked Tolkien studies right away (the first thesis came out within a year or two of the book's publication) and shows no sign of ceasing all these decades later.
So, while Tolkien's current status doesn't fulfill all of Marler's conditions -- something which in itself accurately reflects Tolkien's still uncertain status as he edges ever closer to acceptance within the academy (or what's left of it) -- the signs are promising. And that's not even taking into account the establishment of TOLKIEN STUDIES as a well-respected peer-reviewed dedicated journal nor the extraordinary number of books on Tolkien's works published in the last forty-five years.
*thanks to Doug Anderson for recommending this one.
**she quotes another scholar that the establishment of such a Society serves as "a kind of predictive index to that figure's scholarly weight" (ibid).